This disclosure relates to semiconductor devices and, more particularly, to semiconductor devices including a field effect transistor.
Semiconductor devices are widely used in an electronic industry because of their characteristics such as small size, multi-function, and/or manufacture costs. A field effect transistor (hereinafter, referred to as ‘a transistor’) is used as one of important discrete elements constituting semiconductor devices. Generally, a transistor may include a source region, a drain region spaced apart from the source region, and a gate electrode disposed over a channel region between the source region and the drain region. The gate electrode may be insulated from the channel region by a gate oxide layer.
As semiconductor devices have been highly integrated, certain characteristics of transistors have deteriorated. For example, a short channel effect may be caused in transistors, and turn-on currents of transistors may be reduced. Thus, various research is being conducted for improvement of characteristics of transistors.